Apparatus for positioning stage drops



Jan. 12, 1965 R. A. DREW 3,165,296

APPARATUS FOR POSITIONING STAGE DROPS Filed Aug. 14. 1961 prevent movement of the cable.

United States Patent 3 165 296 APPARATUS FOR PdSITIONING STAGE DROPS Richard A. Drew, Encino, Calif., assignor to Curran Productions, Hollywood, Calif., a corporation of California Filed Aug. 14, 1961, Ser. No. 131,247 11 Claims. (Cl. 254-141) The present invention relates to apparatus for raising and lowering stage drops.

In the past, stage drops such as portions of scenery, curtains or the like have been raised and lowered by a manual operation. Such prior art techniques are time consuming, generally inaccurate and require a great many operators. For example, a theatrical stage may employ.

as many as 60 different stage drops which are brought to stage level at different times and lifted above the stage or into a loft area when not in use.

' The above disadvantages of the prior art apparatus for positioning stage drops are overcome by the present invention. In accordance with the present invention, a movable support member is provided for supporting a stage drop. A head block such as a pulley having a plurality of grooves is mounted adjacent the top position of the stage drop. An arbor adapted to carry weights for counterbalancing the stage drop is preferably disposed below the head block. A plurality of flexible supporting cables are disposed over the head block and connected at one end to the support member and at the other end to the arbor. A control cable is connected at each end to the arbor and means for supporting the control cables above and below the arbor are provided so that the arbor is moved in a downward direction when the control cable isvmoved in one direction and the arbor is moved in an upward direction when the control cable is moved in the other direction. An electric motor is coupled to the control cable. A source of energizing potential is connected to the motor through motor control means for controlling the motor to selectively raise and lower the arbor and thereby raise and lower the stage drop.

In the preferred embodiment braking means are coupled to the cable with means such as a spring for normally biasing the braking means in a braking position to First brake releasing means such as an electrically actuated solenoid are coupled to the braking means and to the source of energizing potential for releasing the braking means from engagement with the cable in response to the energizing potential, whereby the braking means automatically brakes the control cable and stops the movement of the arbor and the stage drop in the event that the source of energizing potential fails.v Second brake releasing means are provided for selectively releasing the braking means from engagement with the control cable whereby the control cable may be moved independently of the operation of the motor. Thus in the event of an electrical power failure, the stage drop will be immediately stopped but may then be controlled manually.

h The invention is described'in more detail in reference v to the accompanying drawing in which a stage drop such as a curtain or the like is connected to a movable support member or pipe 12 by means of cables 14. A head block 16 which may be a pulley having a plurality of grooves is mounted. adjacent the top position of the stage drop 10 or in the loft area of a suitable theatrical stage.

An arbor 18 including a top member 19 and a bottom member 20 connected by rods 21 is adapted to carry counterbalancing weights 22. The members 19 and 20 v are provided with guide grooves 23 which engage or guide rod 23A to guide the movement of the arbor. The total weight of the arbor and the balancing weights 22 is 3,165,296 Patented Jan. 12, 1965 guide pulley 26 is positioned above the supporting member 12 for guiding each of the support cables 24 as shown to maintain the supporting member 12 preferably in a hor zontal position. A control cable 28 including a portion of chain 29 is connected at each end to the arbor 18 and disposed over the head block 16. An idler sprocket 30 and a drive sprocket 32 are rotatably mounted below the arbor 18 in engagement with the chain 29 so that the arbor is moved in a downward direction when the control cable is moved in one direction and the arbor is moved in an upward direction when the control cable is moved in the other direction as illustrated.

An electric motor 34 which may be of the direct current type includes a shaft 35 which is coupled to the drive sprocket 32 by means of electrically actuated clutch 38. An electrically actuated brake 40 having an input circuit 41 is provided to engage the shaft 35 of the motor 34 in the absence of a predetermined energizing current applied to the input circuit 41 thereof. A source of energizmg potential 44 which may be an alternating current voltage is provided to supply the electrical power for the motor 34. The clutch 38 is connected to the source of energizing potential 44 through an auto transformer 39. The auto transformer 39 includes a pair of stationary taps 39A and 39B and a movable contact 39C which selectively engages one of the taps 39A or 398. When the contact 39C is in engagement with the tap 39A the clutch 38 is energized at its maximum current rating so that the shaft 35 may move the arbor 18 and the stage drop 10 even though the counter weight on the arbor 18 does not balance the weight of the stage drop 10. Thus when the clutch 38 is carrying its maximum current the arbor 18 may be lowered by means of the motor 34 to permit the weights to be placed on or taken 01f of the arbor 18 to balance the arbor 18. When the stage drop 10 is balanced by the weights on the arbor 18 the movable contact 390 is switched to the tap 39B to provide a decreased current flow through the clutch 38 for normal operation for the apparatus. This decreased energization of the clutch 38 Will not permit the shaft 35 to move the arbor 18 unless the weights on the arbor 18 approximately counterbalance the weight of the stage drop it). This prevents the motor-35 from carrying an unbalancedweight distribution during normal operation.

A motor control circuit 46 is connected between the source of energizing potential '44 and the motor 34 to control the energization of the motor 34 and the direction of rotation of the shaft 35. An up switch 47, a down switch 48 and a stop switch 49 are coupled to the motor control circuit 46 for controlling the energization of the motor 34 to drive the sprocket 32 and thereby raise, lower and stop the movement of the stage drop 10, respectively.

' The motor control circuit 46 may be of any well known type. For example, the circuit 46 may employ thyratrons to control the energization of the armature of the direct current motor where the source of energizing potential 44 produces alternating current. The motor 34 may have a shunt or series field winding suitably excited by the control circuit 46 as is well known in the art. To reverse the operation of the DC. motor 34 it is only necessary to reverse polarity of the energizing current applied to the armature thereof and to vary the speed it is only necessary to vary the magnitude of the energizing voltage (armature voltage).

current is supplied to the motor 34 to cause the shaft 35' to rotate, the brake 40 releases and permits the motor 34 to raise or lower the stage drop 10. As soon as the arbor for balancing the stage drop,-a plurality. of flexible energizing current to the motor 34 reduces to zero or approximately zero the brake 41 engages the shaft 35 to stop the movement of the. drive sprocket 32 and main tain the stage drop 1'9 in the desired position. v

To prevent the stage drop and arbor 18 from driftbrake sprocket 50 is rotatably mounted in engagement with the chain 29. A pair of idler sprockets 51 maintain the chain in engagement with the sprocket 50'. A brake indicated generally at 52 is coupled to the brake sprocket St for braking or preventing the rotation of sprocket 50 and thereby the movement of the control cable 28. A helical spring 54 is connected to the brake 52 by means of a lever arm 55 rotatably mounted on a shaft 53 to normally actuate the brake and prevent movement of the brake sprocket 50. An electrically actuated solenoid 54? is coupled to the lever arm 55 and has an input circuit 58 which is connected to the source of energizing potential 44. The solenoid 56 upon energization by the energizing potentialfrom the source 44 releases the brake 52 by rotating the lever arm 55 in a clockwise direction. Thus, as long as the source of energizing potential 44 is operative to provide power for the motor 44, the brake 52 is released by means of the brake release solenoid 52. In the event of a power failure, it may be necessary to manually raise and lower the stage drop 10. To permit this operation a second brakerelease-means comprising a rod oil is provided which is arranged to selectively engage the lever arm 55 and rotate it in a clockwise direction to release the brake 52. ,The rod 60 may be manually depressed by a hand operated knob 62. i A helical spring 64 is connected between the rod 60 and asupporting member 66 which also supports the lever arm 55.

The spring 64 normally biases the rod 60 in an upward I direction to prevent contact with the lever arm55. The

rod 60 includes a groove 61 in the top portion thereof which is adapted to cooperate with a brake releasing slidably mounted pin 70. The brake releasing pin 70 may be inserted into the groove 61 to maintain the rod 60 in a I depressed position to release the brake 52.

shaft 35 has rotated through a predetermined number of' revolutions. The switch 74 is also connected to the motor control circuit 46 for de-energizingthe motor 34 when the arbor 18 reaches a preselected intermediate position as determined by a particular number. of revolutions for the shaft 35 Thus the stage drop 10 may automatically be raised or lowered to any desired position by means of one or more intermediate switches similartto 74. I

' A hand rope 80 is disposed over the head block 16, a lower pulley 82 and connected at each end to the arbor weightson the. arbor approximately balance the stage 18 to permit the stage drop 10 to be positioned manually if desired.

What is claimed is: p 1. In an apparatus utilizinga source of energizingpotential for raising and lowering a stage drop the combination which comprises a movable elongated support member for supporting the stage drop, a head block, an arbor disposed below the head block, weights carried by the supporting cables disposed over the headblock and connected at one end tothe support member and at the other end to the arbor, a control cable connected at each end to the arbor, means for supporting the control cable above the arbor so that the arbor is moved in a downward direction when'the control cable is moved in one direction and the arbor is moved in an upward direction when the control cable is moved in the other direction, a rotatably mounteddrive member disposed in engagement with the control cable so that the control cable is moved when the drive member is rotated, an'electric motor, an electrically actuatedclutch connected between the drive member and the motor, a motor control circuit connected between the source of energizing potential and the motor to supply energizing current to the, motor to selectively drive the motor in a forward and reverse direction to raise and lowerthe stage drop, means for connecting the clutch to the source of energizing potential for the motor so that the clutch connects the motor to the drive member in response to the energizing potential and disconnects the motor from the drive member in the absence of the energizing potential, the last named means being arranged to selectively energize the clutch with a first and a second predetermined energizingcurrent so that when the clutch is. energized with the first predetermined energizing current the clutch will connect the motor to the drivemember to move the arbor in a down ward direction even though the weights on the arbor do not balance the stage drop and when the clutch is energized by the second predetermined current the clutch will connect the motor to the drive member ,only when the drop.

2. ,In an apparatus utilizing a source of energizing po-t tntial for raising and lowering a stage drop the combination which comprises a 'movable elongated support member for supporting the stage drop, a head block, an arbor disposed below the head block, weights carried by the arbor'for balancing the stage drop, a plurality of flexible supporting cables disposedover the head block and connected at one end tothe support. member and at the other end to the arbor, a control cable connected at each end to the arbor, means for supporting the control cable above the arbor so that the arbor is movedin a downward direction when the control cable is moved in one direction and the arbor ismoved in an upwarddirection when the control cable is moved in the other direction, a" rotatably mounted drive memb'er disposed in engagement with the control cable so that the control cable is moved when the, drive .,member is rotated, an electric motor, an electrically actuated clutch connected'between the drive member and the 'rnotor, a motor control circuit connected between the source or energizing potential and the motor to supply energizing 1 current to the motor to selectively drive the motor in a forward and reverse direction to raise and. lower the stage drop, means for connecting the clutch to the; source of energizing potential for the motor so'thatthe clutch connects the motor to the drive member-in response to the energizing potential and disconnects the motor from the drive member in the absence of the energizing potential,

. and an electrically actuatedbrake connected'between the clutch and the motor and responsive to .thecnergizing current applied to the motor to brake the drive member,

5. The combination as defined in claim 2 including a braking member for engaging the control cable, means for biasing the braking member into engagement with the cable, first brake release means connected across the source of energizing potential for releasing the braking means from engagement with the cable in response to the energizing potential and second brake release means for selectively releasing the braking means from engagement with the cable.

6. In an apparatus for raising and lowering a stage drop the combination which comprises a movable support member for supporting the stage drop, a rotatably mounted head block, an arbor disposed below the head block, weights carried by the arbor for counterbalancing a stage drop, a plurality of flexible supporting cables disposed over the head block and connected at one end to the support member and at the other end to the arbor, a control cable disposed over the head block and connected at each end to the arbor, means for supporting the cable below the arbor, the control cable including at least a preselected length of chain, a rotatably mountcd drive sprocket in engagement with the chain, a direct current motor including a shaft, a clutch connected between the drive sprocket and the shaft of the motor, a first electrically actuated brake having an input circuit coupled to the shaft of the motor and arranged to engage the shaft in the absence of an energizing current applied to the input circuit thereof, a source of energizing potential, motor control means connected between the source of energizing potential and the motor for applying energizing current to the motor to control the direction of rotation of the shaft of the motor, means for connecting the input circuit of the first brake to the motor control means to release the first brake from engagement with the motor shaft in response to an energizing current applied to the motor, means for connecting the clutch to the source of energizing potential so that the clutch is engaged in response to the energizing potential, a rotatably mounted brake sprocket in engagement with the chain, a second brake coupled to the brake sprocket for normally preventing rotation of the brake sprocket, first brake release means coupled to the source of energizing potential for releasing the second brake in response to the energizing potential, and second brake release means for selectively releasing the second brake whereby the control cable may be manually operated in the event of a failure of the source of energizing potential.

7. The combination as defined in claim 6 including a top limit switch and a bottom limit switch positioned in the line of travel of the arbor and coupled to the motor control means for de-energizing the motor when the arbor has reached a predetermined top and bottom position respectively.

8. The combination as defined in claim 7 including means for de-energizing the motor when the arbor has reached a preselected position between said top and bottom positions.

9. In an apparatus for raising and lowering a stage drop the combination which comprises: a movable sup port member, a head block, an arbor, weights carried by the arbor for counterbalancing the stage drop, a plurality of flexible supporting cables disposed over the head block and connected at one end to the support member and at the other end to the arbor, a control cable connected at each end to the arbor, means for supporting the control cable above and below the arbor so that the arbor is moved in a downward direction when the control cable is moved in one direction and the arbor is moved in an upward direction when the control cable is moved in the other direction,an electric motor coupled to the control cable, a source of energizing potential for the motor, motor control means for controlling the motor to raise or lower the arbor and thereby raise or lower the stage drop, braking means coupled to the cable, means for normally biasing the braking means in a braking position to prevent movement of the cable, first brake releasing means coupled to the source of energizing potential for releasing the braking means, and second brake releasing means for selectively releasing the braking means from engagement with the control cable whereby the control cable may be moved independently of the operation of the motor.

10. In an apparatus utilizing a source of energizing potential for raising and lowering a stage drop the combination which comprises a movable elongated support member for supporting the stage drop, a head block, an arbor disposed below the head block, weights carried by the arbor for balancing the stage drop, a plurality of flexible supporting cables disposed over the head block and conneoted at one end to the support member and at the other to the arbor, a control cable connected at each end to the arbor, means for supporting the control cable above the arbor so that the arbor is moved in a downward direction when the control cable is moved in one direction and the arbor is moved in an upward direction when the control cable is moved in the other direction, a rotatably mounted drive member disposed in engagement with the control cable so that the control cable is moved when the drive member is rotated, an electric motor, a motor control circuit connected between the source of energizing potential and the motor to supply energizing current to the motor to selectively drive the motor in a forward and reverse direction to raise and lower the stage drop, braking means coupled to the control cable for normally preventing movement of the cable, first brake release means coupled to the source of energizing potential for releasing the braking means to permit movement of the cable in response to the energizing potential and second brake release means for selectively releasing the braking means whereby the control cable may be manually operated in the event of a failure of the source of energizing potential.

11. The combination as defined in claim 10 including means coupledlto the drive member and to the motor control circuit for stopping the motor when the arbor reaches a predetermined position.

References Cited in the file of this patent UNITED STATES PATENTS 791,536 Cleal June 6, 1905 1,019,091 Sacerdoti Mar. 5, 1912 1,340,066 Lemle ,May 11, 1920 1,459,358 Buchenberg June 19, 1923 2,936,052 Snarr May 10, 1960 2,942,879 Izenour June 28, 1960 

1. IN AN APPARATUS UTILIZING A SOURCE OF ENERGIZING POTENTIAL FOR RAISING AND LOWERING A STAGE DROP THE COMBINATION WHICH COMPRISES A MOVABLE ELONGATED SUPPORT MEMBER FOR SUPPORTING THE STAGE DROP, A HEAD BLOCK, AN ARBOR DISPOSED BELOW THE HEAD BLOCK, WEIGHTS CARRIED BY THE ARBOR FOR BALANCING THE STAGE DROP, A PLURALITY OF FLEXIBLE SUPPORTING CABLES DISPOSED OVER THE HEAD BLOCK AND CONNECTED AT ONE END TO THE SUPPORT MEMBER AND AT THE OTHER END OF THE ARBOR, A CONTROL CABLE CONNECTED AT EACH END TO THE ARBOR, MEANS FOR SUPPORTING THE CONTROL CABLE ABOVE THE ARBOR SO THAT THE ARBOR IS MOVED IN A DOWNWARD DIRECTION WHEN THE CONTROL CABLE IS MOVED IN ONE DIRECTION AND THE ARBOR IS MOVED IN THE UPWARD DIRCTION WHEN THE CONTROL CABLE IS MOVED IN THE OTHER DIRECTION, A ROTATABLY MOUNTED DRIVE MEMBER DISPOSED IN ENGAGEMENT WITH THE CONTROL CABLE SO THAT THE CONTROL CABLE IS MOVED WHEN THE DRIVE MEMBER IS ROTATED, AN ELECTRIC MOTOR, AN ELECTRICALLY ACTUATED CLUTCH CONNECTED BETWEEN THE DRIVE MEMBER AND THE MOTOR, A MOTOR CONTROL CIRCUIT CONNECTED BETWEEN THE SOURCE OF ENERGIZING POTENTIAL AND THE MOTOR TO SUPPLY ENERGIZING CURRENT TO THE MOTOR TO SELECTIVELY DRIVE THE MOTOR IN A FORWARD AND REVERSE DIRECTION TO RAISE AND LOWER THE STAGE DROP, MEANS FOR CONNECTING THE CLUTCH TO THE SOURCE OF ENERGIZING POTENTIAL FOR THE MOTOR SO THAT THE CLUTCH CONNECTS THE MOTOR TO THE DRIVE MEMBER IN RESPONSE TO THE ENERGIZING POTENTIAL AND DISCONNECTS THE MOTOR FROM THE DRIVE MEMBER IN THE ABSENCE OF THE ENERGIZING POTENTIAL, THE LAST NAMED MEANS BEING ARRANGED TO SELECTIVELY ENERGIZE THE CLUTCH WITH AA FIRST AND SECOND PREDETERMINED ENERGIZING CURRENT SO THAT WHEN THE CLUTCH IS ENERGIZED WITH THE FIRST PREDETERMINED ENERGIZING CURRENT THE CLUTCH WILL CONNECT THE MOTOR TO THE DRIVE MEMBER TO MOVE THE ARBOR IN A DOWNWARD DIRECTION EVEN THROUGH THE WEIGHTS ON THE ARBOR DO NOT BALANCE THE STAGE DROP AND WHEN THE CLUTCH IS ENERGIZED BY THE SECOND PREDETERMINED CURRENT THE CLUTCH WILL CONNECT THE MOTOR TO THE DRIVE MEMBER ONLY WHEN THE WEIGHTS ON THE ARBOR APPROXIMATELY BALANCE THE STAGE DROP. 